In recent years, display components in image display devices including television devices are being shifted from conventional cathode-ray tube displays to thin displays, such as liquid crystal displays and plasma displays. With the thin displays, thicknesses of the image display devices can be decreased. Because liquid crystal panels do not emit light, liquid crystal display devices including liquid crystal panels require backlight devices. The backlight devices are classified broadly into a direct type and an edge-light type based on mechanisms. Each edge-light type backlight device includes a light guide plate and an optical member. The light guide plate is for guiding light from a light source arranged at an end. The optical member is for supplying even planar light converted from the light from the light guide plate with optical effect added thereto to a liquid crystal panel. A backlight device in Patent Document 1 below has been known as an example. Patent Document 1 discloses a configuration in which cylindrical lenses are disposed on a light emitting surface of a light guide plate to have a light collecting function and a prism sheet is disposed on a light exiting surface.